An attempt of reducing power consumption of a source driver and a display device has been attempted. For example, a display device in which when video signals input to each of a plurality of pixels are not changed during a plurality of frame periods, i.e., when a still picture is displayed, power consumption is reduced by stopping operation of a shift register included in a source driver; and a method for driving thereof have been proposed (see patent document 1).
As the other example, a display device, in which power consumption is reduced by stopping operation of a shift register included in a source driver in a case where a video signal input during a period of selecting one certain row of a plurality of pixels is equal to a video signal input during a period of selecting a previous row, and a method for driving the display device have been proposed (see patent document 2).    [Patent Document 1]: Japanese Patent Application Laid-Open No. 2002-169499    [Patent Document 2]: Japanese patent Application Laid-Open No. 2003-44017
In a conventional source driver, even when video signals input to all pixels in one row of a plurality of pixels are equal to one another, the video signals corresponding to all of the pixels in one row have been sampled.